^I like Symbiosis because I think the aliens provide a lot a tension and surprises and a good ethical dilemma for Picard and Crusher. I found the plight of the Onarans very gripping and there was some real great scenes with the actor who plays Kirk's son, including one where he almost kills Riker with his electrical energy. I thought the guest stars were topnotch and the episode has some of my favorite scenes between Picard and Crusher. But to each his own.
At the very beginning of the episode, there was a certain amount of mystery and suspense that seemed promising, I agree. The 'suprise' factor was artificially dragged out a bit when Dr. Crusher took multiple scenes to finally say what the entire audience had already figured out - that the medicine was an addictive drug. But I actually do think the concept had potential. I would not have been opposed to seeing a later series attempt a more nuanced, well though out version of it. But for me, the dilemma is completely undermined by the extremely ham-handed and dumb application of the prime directive, especially once Picard starts labeling his own choices as PD violations yet still goes on about the PD being sacrosanct.
Still, it's because of these positive factors that I do consider this episode higher than several others from this season. It isn't the worst of the bunch by any means.